Tag to be used with the master branch of atlas/athena. Update(s) since 2.0.39: - Re-introduced the creation of a packages.txt file for each ATLAS project; - Introduced a test in atlas_install_headers(...) for the existence of the specified directory; - Added improvements/fixes to FindNjet.cmake, FindOpenLoops.cmake and FindSuperchic.cmake; - Upgraded to Acts v0.10.04.